Mine roof prop and advancing arrangement



y 1968 H. ROSENBERG 3,381,586

MINE ROOF PROP AND ADVANCING ARRANGEMENT Filed June 6, 1966 4 Sheets-Sheet l ll ,6 f

FIG./ L9

INVENTOR- HARRY nnsmfi A TTa/Q/VE v.5

y 1968 H. ROSENBERG 3,381,586

MINE ROOF PROP AND ADVANCING ARRANGEMENT Filed June 6, 1966 4 Sheets-Sheet 3 I/ II 7 2 FIG. 5

INVENTOR- HARFlb RUSENBERG BY M t y 68 H. ROSENBERG 3,381,586

MINE ROOF PROP AND ADVANCING ARRANGEMENT Filed June 6, 1966 4 Sheets-Sheet 4 IN VEN TOR HARRY RUSENBE 5 BY United States Patent Office 3,381,586 Patented May 7, 1968 3,381,586 MINE ROOF PROP AND ADVANCING ARRANGEMENT Harry Rosenberg, Ludinghausen, Germany, assignor to Gewerkschaft Eisenhutte Westfalia, Wethmar, near Lunen, Westphalia, Germany Filed June 6, 1966, Ser. No. 555,346 Claims priority, application Germany, June 10, 1965,

43,831 11 Claims. (Cl. 91-217) The present invention relates to a mine roof prop and advancing arrangement for use with an elongated mining conveyor, including a pair of mining prop frames coupled together for alternate advancement with respect to one another and a conveyor advancing means connected to one of the prop frames, and more particularly to such an arrangement including control valve means which control the operation of the conveyor advancing means in dependence upon changes in the force of the pressure fluid medium, such as hydraulic fluid, used to operate the prop frame arrangement.

In longwall mining operations the mine roof must be properly supported in the vicinity of the mine face being worked, usually by a planer or other mining machine in operative engagement with the mine face, such that as new layers of mineral are exposed at the mine face, the prop frame arrangement for supporting the roof must be advanced progressively toward the new mine face. Generally, an elongated mining conveyor of the conventional type is disposed adjacent the mine face and the planer or other mining machine is mounted thereat for travel along the mine face with the conveyor serving as a guide to maintain the planer or other mining machine in constant pressure engagement with the mine face to achieve eflicient extraction of mineral therefrom. Thus, as new layers of mineral are exposed, not only the prop frame arrangement but also the conveyor must be advanced toward the new mine face.

For this purpose, a conveyor advancing means, such as a piston-cylinder means, is connected at one end to one of the prop frames of an advanceable pair of prop frames while the other end of such piston-cylinder means is placed in operative engagement with the conveyor. Accordingly, the conveyor advancing piston-cylinder means may urge the conveyor toward the mine face and in turn urge the mining machine in pressure engagement with the mine face. When new layers of mineral are exposed, the conveyor advancing means will urge the conveyor forward toward the new mine face since the conveyor advancing means is reinforced against rearward displacement by reason of the connection thereof to one of the prop frames of an advanceable pair. In the same Way, the advanceable mining prop frame system may be moved in the forward direction to provide the desired support of the mine roof in the vicinity of the new mine face and to permit the advancing conveyor piston-cylinder means to retract and thus provide a new increment of amplitude in order to advance the conveyor progressively as further layers of mineral are exposed at the mine face.

In US. Patents 3,169,377, 3,174,289, 3,186,179, 3,192,- 722, and 3,225,547, conventional prop frame arrangements are shown including a pair of prop frames interconnected by piston-cylinder means, which may be termed walking cylinders, whereby when one prop frame is extended into supporting engagement with the mine roof and the other prop frame retracted from such engagement, then the retracted prop frame may be advanced by the walking cylinder, using the extended prop frame as reinforcement. The opposite operation is carried out in the same way upon extending the retracted prop frame into engagement with the mine roof and retracting the previously extended prop frame from such engagement while energizing the walking cylinder to achieve the reverse relative displacement of the walking cylinder and in turn the forward advancement of the particular prop frame in question. This concept may be termed the step ping or walking of a pair of prop frames using a stepping or walking cylinder to achieve the same.

As will be appreciated from US. Patent 3,192,722, in particular, the pair of walking prop frames may include a conveyor advancing means connected thereto which is designed to urge the conveyor in the forward direction of ,advance of the prop frames. The free end of the conveyor advancing means may be pivotally connected directly to the conveyor in one manner or another, or merely be adapted to abut the adjacent side wall of the conveyor, whereby to urge the conveyor in the desired forward direction of advance toward the mine face being worked. In accordance with certain embodiments shown in aforesaid US. Patent 3,192,722, the conveyor advancing means may take the form of a conveyor advancing piston-cylinder means attached to one of the prop frames of a pair, such that the displaceable member of the pistoncylinder means may urge the conveyor in the desired way. In the past, the pressure fluid medium, such as hydraulic fluid, for energizing the conveyor advancing pistoncylinder means was controlled manually and the same was true of the pressure fluid medium for operating the pair of walking prop frames.

Obviously, the purpose for connecting the conveyor advancing piston-cylinder means to one of the prop frames is to achieve reinforcement when such prop frame is in extended position in supporting engagement with the mine roof, so that the urging of the conveyor in the forward direction may take place efficiently. Also, the constant advancement of the conveyor advancing pistoncylinder means in a more or less automatic manner is assured so as to renew the amplitude of such conveyor advancing means when the prop frame to which such conveyor advancing means is connected is brought forward toward the conveyor.

Actually, in the most common forms of the advancing apparatus described, the conveyor advancing pistoncylinder means is attached to the conveyor by means of a fastening bar, while the rearward support of such pistoncylinder means is provided by an arm extending from one of the frames of the walking prop frame pair, or else the thrust of the conveyor advancing piston-cylinder means is achieved, for example, by a non-form fitting transmission to the conveyor via a buffer piece under high friction, again using one of the prop frames as rear support and reinforcement. Additionally, a pivot connection in place of free abutment with the conveyor may be provided for the conveyor advancing means as aforesaid. In another common system used, the rear support of the conveyor advancing piston-cylinder means is provided in the form of a cable which is attached between the adjacent prop frames of separate prop frame pairs situated next to one another, such that the rearward portion of the conveyor advancing piston-cylinder means is displaceably mounted on such cable while the forward portion of such conveyor advancing piston-cylinder means is fastened to the conveyor, as aforesaid, such as by means of a fastening bar, or the like.

In order to attain the walking advancement of a pair of walking prop frames, it has always been necessary to switch the control valve for the hydraulic fluid to the conveyor advancing piston-cylinder means to the retract position before the appropriate prop frame connected therewith, now retracted, could be advanced. The reason for this is that the Walking cylinder to which the prop frames are connected for alternate advancement in step- 35 wise manner is not designed to operate against the pressure of the conveyor advancing piston-cylinder means in turn disposed in urging engagement with the conveyor. Since the conveyor advancing piston-cylinder means, as noted above, is usually attached to one of the prop frames of a pair at a certain distance from such prop frame, i.e. by an arm extending outwardly laterally from such frame, any attempt to operate the walking cylinder for the appropriate prop frame against the existing pressure of the hydraulic fluid in the conveyor advancing piston-cylinder means would entail a great strain on the lower framework construction of the prop frame system in question.

Experience has shown that an additional source of trouble arises by the necessity of operating the conveyor advancing piston-cylinder means before operating the walking cylinder for the given prop frame pair. This is true since unless the conveyor advancing piston-cylinder means has previously been switched to the retract position, the prop frame system cannot be advanced without the disadvantages noted above. The omitted operation has to be performed in order to avoid excessive strains as aforesaid and because of the nature of the construction the cause of the trouble is usually recognized quickly. On the other hand, after advancement of the particular prop frame system, if the conveyor advancing piston-cylinder means is not switched back to the extended position, this source of trouble will not be detectable at first, since the lack of advancing pressure for the conveyor advancing piston-cylinder means is not apparent without inspection of the valve setting therefor. Accordingly, when the mining machine, such as a planer, is displaced along the conveyor, trouble is caused by the failure of the conveyor to urge the planer against the mine face in the operative manner. The mining machine will thus not be able to achieve its purpose efliciently. In such instance, the conveyor in essence is forced away from the mine face as the mining machine passes since the conveyor advancing piston-cylinder means fails to urge the conveyor in the desired direction. Tracking down this source of trouble severely taxes the operating personnel, especially because of the number of such arrangements in the distance along the longwall mine face being worked and the necessity for rechecking the prevailing disposition of the various conveyor advancing piston cylinder means.

It is an object of the present invention to overcome the foregoing drawbacks which occur in the separate operation of the conveyor advancing piston-cylinder means and of the walking cylinder for the Walking prop frame system, and to provide an over-all system which will assure the operating personnel that, when the appropriate prop frame is advanced by the walking cylinder, the frame to which the conveyor advancing piston cylinder means is attached will not work against the pressure of such conveyor advancing piston-cylinder means.

It is another object of the present invention to provide an arrangement of the foregoing type in which the control valve means for the pressure fluid medium energizing the conveyor piston-cylinder means will be influenced by the prevailing force of the pressure fluid medium used to energize the walking of the prop frames, so as to attain in an automatic manner the walking of the prop frames without working against the force of the pressure fluid medium of the conveyor advancing piston cylinder means.

It is still another object of the present invention to provide such an arrangement in which the control valve means for the conveyor advancing piston-cylinder means will normally maintain the conveyor advancing pistoncylinder means in extended position so long as the appropriate prop frame to which the same is connected is in extended position and engagement with the mine roof whereas when such a prop frame is released from such engagement to attain the retracted position thereof, then such control valve means will create a prevailing nonpositive pressure fluid medium force in the conveyor advancing piston-cylinder means, either by way of an opposite force serving to retract such piston-cylinder means or by way of a neutral, equalized pressure circuit permitting suitable retraction thereof under the force of the walking cylinder when such appropriate prop frame is advanced, whereby to relieve the overall system from excessive strain under the operating conditions.

It is a still further object of the present invention to provide such a control valve means including a manual overtake position which may be operated alternately to the automatic operation described in dependence upon the force of the fluid pressure medium used to achieve the advancement of the walking prop frame system.

Other and further objects of the present invention will become apparent from a study of the within specification and accompanying drawings, in which:

FIG. 1 is a schematic top view of a walking prop frame arrangement in accordance with one embodiment of the invention, having a conveyor advancing pistoncylinder means interconnecting one of the prop frames with the conveyor,

FIG. 2 is a schematic view of the flow lines for the pressure fluid medium used to operate the props of one of the prop frames of the pair and with which the con- 'veyor advancing piston-{cylinder means is connected, showing as well the automatic control operation of the valve means for supplying pressure fluid medium to the conveyor advancing piston-cylinder means, such flow system being indigenous to the arrangement of FIG. 1,

FIG. 3 shows a similar walking prop frame arrangement to that of FIG. 1, including conveyor advancing piston-cylinder means interconnecting one of the prop frames with conveyor via an abutment block rather than a fastening bar as in the case of FIG. 1,

FIG. 4 is a view similar to FIG. 2 of the flow line arrangement used to operate the system shown in FIG. 3 in accordance with the present invention,

FIG. 5 is a schematic view showing a pair of walking prop frame units operatively attached via an interconnecting cable with the conveyor piston-cylinder means which is in turn connected to the conveyor by a fastening bar, and

FIG. 6 is a schematic view of a flow system for the pressure fluid medium, similar to the arrangement shown in FIGS. 2 and 4, yet'indigenous to the operation of the pair of walking prop frame units shown in FIG. 5.

It has been found in accordance with the present invention that an improvement may now be provided in a mine roof and advancing arrangement for use with an elongated mining conveyor, wherein such arrangement includes a pair of pressure fluid medium energized extensible and retractable mining prop frames, pressure fluid medium energized frame advancing motive means having a first motive part and a second motive part operatively interconnected for relative linear movement alternately toward and away from each other, one said frame being connected with one said motive part for linear movement therewith and the other said frame being connected with the other said motive part for linear movement therewith whereby to achieve alternate advancement of said frames with the respective motive part upon corresponding alternate high and low force resultant pressure fluid medium energizing of said frames and said motive means, and auxiliary pressure fluid medium energized conveyor urging piston-cylinder means, including a double acting piston member and a cylinder member operatively interconnected for relative linear movement in a direction alternately toward and away from one another, one said member being connected to one said frame, and the other said member being adapted to engage operatively such mining conveyor to urge such conveyor in a given operative linear direction in dependence upon such relative linear movement between said members. The improvement of the present invention with respect thereto contemplates control valve means for controlling automatically the auxiliary pressure fluid medium for said urging piston-cylinder means and having a biasing counter force normal position and a pressure fluid medium responsive energized position, said valve means in one of said positions permitting positive flow of auxiliary pressure fluid medium to urge said urging piston-cylinder means in one of said alternate directions and said valve means in the other of said positions preventing such positive flow, said valve means being in coupled operative flow communication with the pressure fluid medium used for achieving such alternate advancement of the frames, whereby when the force of said pressure fluid medium used for advancement of the frames exceeds the counter force of the normal position of said valve means said valve means will change to said energized position and when said counter force exceeds the force of said pressure fluid medium used for advancement of said frames, said valve means will change to said normal position, to control automatically the flow of pressure fluid medium for urging the piston-cylinder means in dependance upon the difference between said counter force and the force of said pressure fluid medium used for advancement of the frames and in turn in dependence upon the positive and non-positive flow positions of said valve means.

In accordance with one specific embodiment of the invention, the valve means in said other of said positions closes off the urging piston-cylinder means from flow of auxiliary pressure fluid medium while flow communicating the pressure medium in said cylinder member on both operative sides of the double acting piston member to produce a relatively equalized pressure circuit idle disposition thereof. In accordance with an alternate specific embodiment of the present invention, the valve means in said other of said posi'ions reverses the positive flow of auxiliary pressure fluid medium to the urging pistoncylinder means to urge said urging piston-cylinder means in the other of said alternate directions.

Advantageously, in accordance with another embodiment of the present invention, the valve means also has a manual overtake control position, such that the valve means in one of said positions permits positive flow of auxiliary pressure fluid medium to urge the urging pistoncylinder means in one of said alternate directions, in another of said positions closes off the urging piston-cylinder means from flow of auxiliary pressure fluid medium while communicating the pressure medium in said cylinder member on both operative sides of the double acting piston member to produce a relative equalized pressure circuit idle disposition thereof, and in still another of said positions reverses the positive flow of auxiliary pressure fluid medium to the urging piston-cylinder means to urge such urging piston-cylinder means in the other of said alternate directions.

In this regard, in accordance with one such embodimerit of the invention, the counter force normal position corresponds with said still another of said positions to reverse the flow to urge the piston-cylinder means in said other of said alternate directions, said energized position corresponds with said other of said positions to urge the piston-cylinder means in said one of said alternate directions, and said manual position corresponds with said another of said positions to produce such idle disposition. Alternately, in accordance with another embodiment of the invention, the counter force normal position corresponds with said another of said positions to produce said idle disposition, said energized position corresponds with said one of said positions to urge the piston-cylinder means in said one of said alternate directions, and said manual position corresponds with said still another of said positions to reverse the flow to urge the pistoncylinder means in said other of said alternate directions.

In the latter instance, advantageously, the arrangement may also include an additional said pair of mining prop frames and an additional said frame advancing motive means with corresponding motive parts connected respectively to said additional frames, a linear link means interconnecting said one frame of the first mentioned pair of frames with a corresponding one frame of said additional pair of frames, said one said member being connected to said link means and in turn thereby to said one frame of each said pairs of frames, as Well as an additional said valve means in cooperative aligned tandem flow disposition with respect to said first mentioned valve means and having corresponding valve positions, said additional valve means being in coupled operative flow communication with the corresponding pressure fluid medium used for achieving alternate advancement of said additional frames, whereby when the corresponding force of said pressure fluid medium used for advancement of the first mentioned frames and the corresponding force of the pressure fluid medium used for advancement of the additional frames simultaneously exceed, respectively, the corresponding counter forces of the normal positions of both corresponding valve means said valve means will both change to the corresponding energized positions and when the corresponding counter forces of both said valve means simultaneously exceed the corresponding forces of the pressure fluid media said valve means will both change to the corresponding normal positions, and when said valve means are in correspondingly different positions, said valve means will resultantly produce said idle disposition and will be ineffective to change the existing idle flow condition of said piston-cylinder means, save for manual overtake, until both said valve means again attain simultaneously said energized positions.

Referring to the drawing, in FIG. 1 a mining prop and advancing arrangement is shown including the prop frame unit or pair 1, having the prop frame 2 which contains the upright props 4 as well as the frame 3 which contains the upright props 5, and the walking cylinder 7 composed of the piston rod 8 carrying a piston (not shown) thereon, intermediate the ends of such rod, such that the piston is operatively received within the cylinder 9 with the ends of rod 8 extending outwardly through the end portions of the cylinder 9. The straps 6 interconnect the frame 2 with the ends of rod 8 while the straps 10 interconnect frame 3 with the ends of the cylinder 9, such straps preferably being resilient in nature so as to accommodate unevenness in the mine floor yet maintain the prop frames in the desired relationship. A lateral arm 11 extends laterally outwardly from frame 3 in a direction away from the intermediately positioned walking cylinder 7 and such arm 11 is reinforced by the strut 12 interconnecting arm 11 with frame 3 in an angular manner. The com'eyor advancing cylinder 13 having the cylinder 14 and the double acting piston rod 15 on which is mounted the double acting piston 15a (see FIG. 2) is connected via the pivot 16 to the arm 11 of frame 3 such that the free end of the advancing cylinder 13 extends in a transverse forward direction toward the mining conveyor 19 for connection via the pivot 17 to the fastening bar 18 attached to the side of conveyor 119 remote from the mine face (not shown).

The arrangement shown in FIG. 1 and its operation is similar to arrangement shown in US. Patent 3,192,722, as aforesaid.

Thus, to cause the prop frame pair 1 to he stepped or walked in the direction of conveyor 19, which is also of conventional design and preferably made up of a plurality of individual conveyor sections articulatedly connected to one another in end-t0-end relation, the props of one such frame, which are normally energized by pressure fluid medium such as hydraulic or pneumatic fluid, are maintained in extended position to place the frame in supporting engagement with the mine roof while the props of the other such frame are retracted from such supporting engagement. Hence, the walking cylinder 7 may be energized so that the part thereof connected with the retracted frame will be displaced linearly in the forward direction and in turn such retracted frame, Upon alternate actuation, the retracted frame will be extended and the extended frame will be retracted, so that the walking cylinder '7 may be energized oppositely to drive forward the now retracted frame. Naturally, as the frame 3 is walked forward, the advancing cylinder 13 must retract concomitantly or else the force of the walking cylinder 7 will be transmitted through the arm 11 to the advancing cylinder 13 and in turn to the conveyor 13. This would place an undue strain on the interconnecting parts between the advancing cylinder 13 and the frame 3 and also on the walking cylinder '7.

Normally, manual control valve means are used to supply pressure fluid medium separately to the props of frame 2 and to the props of frame 3, and also manual control valve means are used to supply pressure fluid medium to the end portions of cylinders 9 and 14, respectively, on the opposing sides of the corresponding piston operatively received therewithin, whereby to control the relative linear disposition of the particular cylinder and piston rod with respect to one another in the known manner.

As may be seen from FIG. 2, the operation of the props of the frame 3, to which the advancing cylinder 13 is connected, is coupled with the operation of the advancing cylinder 13 to produce in an automatic manner a concordance of operations to avoid the prior art disadvantages, and especially the disadvantage of strain on frame 3 when being advanced against the prevailing fluid pressure of the advancing cylinder 13. While the flow lines for operating the props of frame 2 and for operating the walking cylinder 7 are not shown, these are conventional as is clear from the aforementioned U.S. patents, and especially US. Patent 3,192,722.

In FIG. 2, the props 5 of frame 3 are shown schematically with the base cylinder portion 5a operatively receiving the upper piston portion Sb so that pressure fluid medium, such as hydraulic or pneumatic fluid, passing through line 20 and in turn branched lines 21 and 22 may be fed to the appropriate cylinder portions 5a and be withdrawn therefrom so as to achieve the simultaneous extension and retraction of the props 5 and in turn the appropriate extension of frame 3 into engagement with the mine roof and retraction from such engagement. The operation of props 5 is controlled by the valve 23, which is usually a manually operated valve but which may also be automatically operated, with fluid medium under pressure being supplied through feed line 27 through check valve 28, schematically shown, and with such fluid medium being withdrawn through discharge line 29 for return to the pressure fluid medium reservoir or main source. Valve 23 is normally biased by spring 24 into the position shown wherein fluid medium is fed through line 27 to the pressure port 30 of valve 23 whereby to fill the cylinder portions 5a of the props 5. The blind port 31 registers with the discharge line 29 in this valve position. Upon displacement of the valve 23 in the direction of arrow 25, against the force of spring 24, by means 26, which may take the form of manual or automatic displacement means, the discharge line 29 registers with the return port 32, so that fluid medium in cylinder portions 5a will return through valve 23 to the reservoir therefor, causing retraction of the piston portions Sb. In such a position of valve 23, blind port 33 registers with feed line 27. This operation of the props of the prop frame in question is well known. However, a branch line 34 is in communication with the main line 28 which extends to the automatic control valve 35 in accordance with the present invention which controls the flow of pressure fluid medium with respect to feed line 36 and discharge line 37, similar to feed line 27 and discharge line 29 and fed from the same or different reservoir or source, and branch lines 38 and 39 to the opposite end portions 40 and 41 of cylinder 14 on the appropriate sides of double acting piston a carried by double acting piston rod 15.

In the position of automatic control valve 35 shown in FIG. 2, the cross ports 44 and 45 register feed line 36 and discharge line 37 appropriately with branch lines 38 and 39, as the case may be, so that pressure fluid medium supplied through feed line 35 enters the end portion 41 while pressure fluid medium in end portion 40 is discharged through branch line 38 and discharge line 37 back to the reservoir or source, thereby causing rod 15 to retract into cylinder 14. Valve 35 is maintained in the position shown by the normally biasing spring 42. Significantly, the force or counter force of spring 42 is lower than the force of the pressure fluid medium fed through line 27 to line 29 and in turn line 34, yet is higher than the force of the pressure fluid medium in line 20 and branch line 34 when valve 23 is placed in the return position at which return port 32 registers line 20 with discharge line 29. In the latter instance, the force of the fluid medium is insufiicient to maintain the prop piston portions 5b in extended position and such parts retract within the appropriate cylinder portions 5a, causing fluid medium under low force to return via port 32 to the reservoir therefor through discharge line 29.

Once valve 23 is returned to its normal position under the biasing force of spring 24, the force of the fluid medium in line 27 will be transmitted through branch line 34 to the automatic piston means, shown schematically at 48, so as to operatively flow connect valve 35 with the fluid medium in lines 20 and 34. When a high force is present in line 34, i.e. when the force of fluid medium in line 27 communicates with line 20, then the means 48 will be urged by such force against the counter force of spring 42 and thereby urge valve 35 to the middle position shown. In such middle position, or energized position, the straight ports 46 and 47 register respectively with the feed line 36 and discharge line 37, thereby communicating the force of the pressure fluid medium in feed line 36 with end portion 40 via branch line 38 while communicating end portion 41 via line 39 and straight port 47 with discharge line 37. This arrangement or position of valve 35 will cause piston rod 15 to be extended.

In this way, the normal operation of valve 35 is under automatic control governed by the force of the prevailing pressure fluid medium in line 20 which operates the extension and retraction of the props of frame 3. Accordingly, when the props of frame 3 are retracted to move frame 3 in the forward direction via walking cylinder 7, then a low force exists in pressure lines 20 and 34 which is overcome by the counter force of spring 42, and accordingly valve 35 is maintained in a normally biased position shown. Then, as frame 3 is walked forwardly, the pressure through feed line 36 will simultaneously cause the retraction of piston rod 15 within cylinder 14, but in any case strain 011 frame 3, formerly caused by the exertion of the force of the walking cylinder against the force of an extended advancing cylinder, will not occur since the retraction of the prop frame in question will be accompanied by the retraction of the advancing cylinder in accordance with the present invention.

Advantageously, valve 35 is also provided with a manual overtake means 51, shown schematically, which may be operated to move valve 35 in the direction of arrow 43 against the force of spring 42 not only to the middle position in such direction as is accomplished where there is a high force in line 2t), but also to the left end position in which the neutral or idle circuit port 49 registers branch lines 38 and 39 with one another as well as with the discharge line 37. Blind port 50 in such a position registers with feed line 36. This will permit piston rod 15 to be displaced in either direction within cylinder 14 without substantial work effort since both sides of piston 15a are in pressure communication through the circuit port 49.

Control valve 35 is only shown schematically in FIG. 2, though it will be appreciated that the same represents a valve element or the like in the form of a rod or piston axially biased in one direction by spring 42 and having a surface axially exposed to the pressure fluid medium in line 34 to cause axial movement in the direction of arrow 43 against the force of spring 42, whereby to place the straight ports 46 and 47, on the one hand, and the cross ports 44 and 45, on the other hand, in registry with branch lines 38 and 39 as well as feed line 36 and return line or discharge line 37, as the case may be. Furthermore, the manual overtake means 51 are provided to permit axial displacement not only as between the cross port and straight port positions mentioned, but also the neutral or idle circuit port position as well by manual displacement further in the direction of arrow 43 than the displacement permitted under the high force of the fluid medium in line 34 required to displace valve 35 to the straight port position.

It will be appreciated by the artisan, that known delay elements may be used in the flow lines in question to delay the timing of actuation of any of the parts above described to produce a desired sequence and concordance of operations. Thus, it may be desirable first to retract the props of frame 3, and then to energize the Walking cylinder 7 immediately upon completion of the retraction and simultaneously with the energizing of walking cylinder 7 also energize valve 35 to achieve the required position to retract the advancing cylinder 13 as frame 3 is advanced and to achieve the advancement of cylinder 13 only after frame 3 has again been extended into supporting engagement with the mine roof, whereby to supply under substantially no strain suitable reinforcement of advancing cylinder 13 in turn to permit the displacement of conveyor 19 in the desired same forward direction.

As the artisan will also appreciate, the branch line 34 may be coupled with the pressure fluid medium line to the walking cyinder 7 rather than to the pressure fluid medium line 20 for the props of frame 3. In such event, the changing of the position of valve 35, above described, may be carried out under the influence of the high and low pressure fluid medium force of the appropriate end portion of the cylinder 9 on either side of the piston (not shown) carried by rod 8 in a more or less simultaneous actuation manner, such that as the walking cylinder 7 advances the appropriate frame 3, advancing cylinder 13 will be made to retract in a linearly proportionate way.

It should be noted that in connection with the embodiment shown in FIG. 1, the fastening bar 18 to which the advancing cylinder 13 is pivotally connected permits the displacement of conveyor 19 to be undertaken in either the forward direction, toward the right as viewed in FIG. 1 or in the return direction, toward the left as viewed Y in such figure. Because of the pivotal connection at 17, and assuming, for instance, that frame 3 is in supporting engagement with the mine roof, then suitable reinforcement exists for the advancing cylinder 13 to be extended so as to force conveyor 19 in the forward direction toward the right as shown in FIG. 1 or to be retracted to displace conveyor 19 toward the left as shown in such figure. Thus, the embodiment shown in FIG. 1 may be termed a pushpull conveyor advancing cylinder useable with a prop frame unit or pair operatively interconnected by a walking cylinder.

In the embodiment shown in FIGS. 3 and 4, which are of similar importance to the embodiment shown in FIGS. 1 and 2, corresponding parts are designated by correspondingly primed reference numerals. In this embodiment, however, the lateral arm 11 extends perpendicularly outwardly and is not provided with a reinforcing strut. Also, the advancing cylinder 13 is of the pusher type whereby to push conveyor 19 in the forward direction, toward the right as viewed in FIG. 3 via the pusher piece 18' attached at 17 to the free end of double acting piston rod 15. The arrangement shown in FIG. 3 may be termed one involving a pusher type conveyor advancing cylinder used with a prop frame unit or pair interconnected for alternate advancement with a walking cylinder.

Since the advancing cylinder 13 is primarily designed to push the conveyor in the forward direction, the arrangement of the valve 35 shown in FIG. 4 is somewhat different from that of valve 35 shown in FIG. 2. All of the appropriate parts shown in FIG. 4 are of similar nature and operation to those shown in FIG. 2 and accordingly the corresponding reference numerals are designated by primes. The main distinction in the automatic control valve 35 of .FIG. 4 over that of FIG. 2 is that the positioning of the cross ports 44' and as well as of the neutral or idle circuit port 49', together with the blind port is reversed. Thus, under the normal biasing force of spring 42', the neutral circuit position of valve 35 will prevail and the piston rod 15' will be able to be displaced without substantial effort in either direction within cylinder 14' due to the fact that end portion 40' and end portion 41' of cylinder 14' are in fiow communication with one another through branch lines 38' and 39 due to the circuit port valve position maintained. This will occur where there is a low pressure fluid medium force in line 20' and branch line 34' insufiicient to overcome the counter force of spring 42'. In this position, the props of frame 3 are retracted from engagement with the mine roof and frame 3' may be energized via walking cylinder 7 to displace frame 3' in the forward direction toward the right as view-ed in the drawing. Upon the attainment of a high pressure fluid medium force in line 20' and branched line 34, when prop frame 3 is extended into engagement with the mine roof, then the force of the pressure fluid medium in line 34' will act on the piston means 48', in a manner similar to the operation of control valve 35 of FIG. 2, whereby to overcome the predetermined force of spring 42 and urge the valve 35' toward the right in the direction of arrow 43. This will achieve the alignment of straight ports 46' and 47' with the lines 38 and 39' similar to the energized position shown in FIG. 2. Accordingly, piston rod 15 will be extended from cylinder 14' to push conveyor 19 in the desired direction. The manual overtake means 51 may be used to vary the positions of valve 35', and especially to achieve the third position at which the cross ports 44' and 45' flow connect the feed line 36 and discharge line 37' with the lines 38 and 39 extending to the cylinder 14'. This latter position is attained when valve 35' is manually displaced in the direction of arrow 43' against the counter force of spring 42', although it will be realized that the manual overtake means 51' may also be used to achieve the middle position of valve 35 in which the straight ports 46 and 47' flow connect lines 36' and 37 with line 38 and 39. Analogous operation of cylinder 13 via valve 35' is achieved in accordance with the arrangement of FIG. 4, i.e. to the operation of cylinder 13 via valve 35 as shown in FIG. 2, with the positioning of the valve settings, i.e. straight ports, cross ports, and neutral circuit port blind port, differing as the case may be to achieve selective automatic and manual operation of cylinder 13 in accordance with the operation of the prop frame pair 1'.

In FIG. 5, an alternate embodiment in accordance with the present invention is shown which is similar to that of FIG. 1 insofar as the structural arrangement is concerned, save for the use of a pair of prop frame units. The parts of FIG. 5 analogous to those of FIG. 1 are designated with double primed numerals. Thus, two separate prop frame units or pairs 1" are provided, each having a frame 2" and a frame 3" operatively interconnected by a cylinder 7", and each having extensible and retractable props of the type contemplated in the arrangement of FIG. 1, with only the props 5" being shown on the respective frames 3". The cable, strap, or other link means 11" interconnects the separate frame units 1" via the appropriate ears 12" such that the piston rod 15" operatively carried within the cylinder 14" of the conveyor advancing cylinder 13" may be connected therewith. Specifically, the retaining guide 16 is disposed on the free end of piston rod 15 so as to displaceably retain therewithin the link means shown in this embodiment in the form of a cable 11". The other end of the advancing cylinder 13" is connected via the pivot 17" t the fastening bar 18" in turn connected to the conveyor 19". The flow lines 38" and 39" are also shown schematically for energizing the advancing cylinder 13".

In this way, regardless of the forward or rearward positioning of one such prop unit 1 with respect to the other, advancing cylinder 13" will be suitably reinforced via the cable 11" so as to urge the conveyor 19 in the desired direction, whether forwardly and downwardly as viewed in FIG. 5 or rearwardly and upwardly as viewed in such figure. This type arrangement is similar to that of FIG. 1 in that a push-pull type conveyor advancing cylinder is contemplated. Suitable alignment of cylinder 13" with respect to cable 11" is possible because of the retaining guide connection 16" whereby displacement of one such frame 1" with respect to the other will either permit cylinder 13 to push or pull the conveyor or will cause the cable 11" to realign itself with respect to that portion on either side of the retaining guide 16".

In accordance with the embodiment of FIG. 5, it will be appreciated that both of the frames 3" must be retracted simultaneously in order to attain the proper and efficient normal advancement of conveyor 19', and the same is true where it is desired to withdraw conveyor 19' in a direction away from the mine face. Accordingly, frames 2" must be extended simultaneously and retracted simultaneously, and frames 3" must be extended simultaneously and retracted simultaneously in opposing concordance with the extension and retraction of the frames 2". Also, the concomitant advancing cylinders 7" must operate simultaneously in the same direction of movement to achieve the desired walking of the prop frames in unison.

For this purpose, as shown in FIG. 6, a similar flow arrangement to that shown in FIGS. 2 and 4 is contemplated, but in this case a pair of valves 23 and lines 20", 21", 22.", and 34 is necessary for the appropriate control of the props of the two frames 3". While still only one advancing cylinder 13" is contemplated, as well as only one set of lines 38 and 39", leading to the respective end portions 40 and 41" of cylinder 14", a pair of tandem superimposed automatic control valves 35a and 35b is utilized. All like parts in FIG. 6 to those contemplated in FIGS. 2 and 4 are shown with corresponding reference numerals having double primes. The operation of valves 35a and 35b is individually the same as the operation of valves 35 and 35' of FIGS. 2 and 4, ex-

cept that the positioning of the settings for the straight ports, cross ports, and neutral circuit port-blind port has been rearranged. In this embodiment, the preloaded springs 42" have a predetermined force maintaining the valves 35a and 35b in the middle position settings, i.e. while exceeding the force ofthe appropriate springs 52 of the manual overtake means 51". However, when the pressure in lines 34 exceeds the counter force of springs 42", as such pressure acts upon the appropriate piston means 48", the piston means 48" will urge against the appropriately positioned springs 42" and overcome the force of springs 42 as well as th force of springs 52, whereby to urge the valves 35a and 35b toward the right as viewed in the drawing to achieve the straight port disposition rather than the normal neutral or idle circuit portion position shown in FIG. 6. This will serve to extend piston rod to urge the conveyor in the desired direction. When the props of the frames 3" are retracted, the low force of the pressure fluid medium in lines 34" will accordingly be overcome by the force of the springs 42 which will then return the valves 35a and 35b to the middle position setting whereupon the frames 3" may be advanced without any substantial counter force from the advancing cylinder 13 due to the idle circuit disposition thereof.

Upon manual overtake via the manual overtake means 51", the setting of the valves 35a and 3511 may be changed at will, preferably to force the valves toward the left as viewed in the drawing to achieve the cross port situation, preferably such that one of the cross port settings of one valve will be aligned with the straight port setting of the other valve.

It will be realized that in the position shown in FIG. 6, the neutral position prevails and this will prevail so long as one of the valves 35a and 35b is maintained in the position shown. Where both of the valves are in the straight port situation, then piston rod 15" will be energized in one direction and where concomitantly one valve is moved to the cross port position while the other remains in the straight port position, the piston rod 15" will be urged in the opposite direction. Where either or or both of the idle circuit port settings is used, the piston rod 15 will be in idle setting disposition, and where both of the cross port settings are aligned, no flow through the valves will occur due to the unidirectional nature of the ports.

In fact it will be appreciated that in each of the embodiments shown the ports are uni-directional in nature which may be accomplished by the inclusion therein of an appropriate check valve.

All of the flow lines may be supplied in all of the embodiments shown from a single source or reservoir of hydraulic or pneumatic fluid. However, the appropriate valve control system of the present invention must beprovided so that the operation of the conveyor advancing cylinder 13, 13, or 13" will be attained in the desired way under the influence of the high or low force pressure fluid medium existing in the flow line to the appropriate prop frame to which the advancing cylinder is connected, or for that matter the appropriate walking cylinder part as aforesaid.

It will be realized that the manual control overtake will permit in a given instance independent operation of the conveyor advancing cyl nder in question as, for example, will be convenient in installing the conveyor advancing cylinder and/or in realigning or shifting of the conveyor and/ or of the prop frame units, depending upon conditions met under actual mining operations. In any instance where the neutral or idle circuit position of the valve is selected, it will be realized that suflicient pressure is present within cylinder 13 or 13 or 13 to prevent displacement from the prevailing position, except under positive force such as that which may be supplied by the walking cylinder through the prop frame being advanced and to which the advancing cylinder is connected. Even in the instance of the embodiment of FIG. 3, where only a pushing contact with the conveyor is made via the conveyor advancing cylinder, a constant contact of the advancing cylinder and the conveyor is assured in the idle circuit disposition. Where it is desired to withdraw the prop arrangement from the conveyor, then in the embodiment of FIG. 3, the advancing cylinder may be retracted.

In contrast to the arrangements shown in FIGS. 1-4, that shown in FIGS. 5 and 6 only permits actuation of the advancing cylinder 13 where both lines 34" are at high pressure sufficient to change the valve settings of valves 35a and 35b from the idlecircuit disposition to the energized setting in which the straight ports of the valves are aligned in tandem. Otherwise, the neutral or idle circuit disposition will exist permitting the prop frames 3 to be advanced without difficulties. Because there is normally no load on the rear support link means or cable 11" as the frames 3 are advanced by the walking cylinders, the conveyor advancing cylinder 13" is able to align itself automatically to the correct position between the adjacent frame pairs 1. This is even true where the walking cylinders are energized to reverse the travel of the frame pairs 1 so that the cable 11" pulls against the cylinder 13 at the retaining groove 16", whereby in 13 turn to pull against conveyor 19" via the pivotal connection 17" and the fastening bar 18".

All in all, therefore, the present invention provides a spring-loaded servo-piston control valve means, which is conventional but which has not been used heretofore in an arrangement of the instant type under constant flow communication with the pressure fluid medium fed to the props of the appropriate prop frame or the walking cylinder part of the appropriate prop frame unit or pair, whereby automatic control of the actuation of the advancing cylinder is attained in concordance with the retraction and/ or extension of the props of the appropriate frame, or with the energizing of the walking cylinder for the frame pair.

Advantageously, in accordance with the present invention, the operation of the prop frame units may now be carried out in an automatic manner without fear of excessive strain on the working parts which had been caused heretofore in connection with the conveyor advancing cylinder connected to one of the prop frames. By way of the present invention, such advancing cylinder is in effect deenergized or placed in non-positive pressure flow with respect to the pressure feed line thereto to permit positive retraction of the advancing cylinder or idle circuit disposition resulting in forced retraction of the advancing cylinder under the forward urgence of the retracted prop frame connected thereto.

As aforesaid, it is advantageous to provide a delaying element, such as a spring, or the like, in the various flow lines to the valves to assure that the necessary switching action required for the conveyor advancing cylinder will be completed before the walking cylinder is energized. Such means are well known and can be incorporated in the system by the artisan forthwith.

It will be realized that since only two of the settings of any of the valves shown herein will be necessary for the normal performance of the logical sequence of operations for urging the conveyor advancing cylinder and/ or the appropriate prop frame in the desired way, depending upon how the coupling between the conveyor advancing cylinder and the conveyor itself is constructed, it is sufficient for the third setting to be manually controllable rather than also automatically controllable as such third setting will not normally be used. Such manually controlled valve setting is intended to serve as an aid in installation, or in the case Where only a pushing connection between the conveyor advancing cylinder and the conveyor is contemplated (see FIGS. 3 and 4), wherein the idle or neutral circuit disposition is selected for the automatic valve operating sequence, then such manual setting may offer the possibility of retracting the conveyor advancing cylinder manually to permit certain work to be done on the chain channels or other parts of the conveyor normally found in the conventional conveyor constructions.

Among the special advantages of the present invention is the fact that the human error source of the operator in manually controlling the energizing of the prop frames and of the walking cylinder, and of the conveyor advancing cylinder, in antagonism to one another, will be avoided and also problems in displacing the conveyor in the desired way and in maintaining the conveyor in positive engagement with the mine face to permit the mining machine to move along the conveyor Without rearward tilting from the mine face as has been caused in the past where a given conveyor advancing cylinder was not properly energized. The arrangement of the present invention, besides freeing the operating personnel from additional work which might otherwise be imposed thereon by problems overcome in the foregoing manner, also provides the advantage that the automatic operation may be interrupted at will by the mechanical overtake position of the particular valve such as, for example, where repairs arenecessary to be made and/or for other reasons it is desired to extend or retract the conveyor advancing cylinder or place the same in idle disposition as aforesaid, i.e. manually.

It will be realized by the artisan that the actuation of the valves for the extension and retraction of the props of a given frame as well as the valves for the conveyor advancing cylinder in accordance with the invention may be ganged by a given linkage (not shown) preferably with an adjustable spring or other delay means in association with the servo-piston automatic control valve of the invention to attain proper timing of the energizing actuations for the various part of the arrangement. Of course, a purely mechanical control is unsuitable for use in hydraulically operated walking prop systems of the instant type where programmed automatic operation is contemplated.

It is also possible to couple together the operation of the prop frames and of the conveyor advancing cylinder by mechanical linkages and preliminary pressurizing control of the particular valves in dependence upon the setting prop pressure, or the like. A threshold valve is thus contemplated which will not permit hydraulic fluid to flow out of the conveyor advancing cylinder pressure line until a sufliciently high pressure has been attained in the feed line to the props of the particular frame.

Therefore, in accordance with the present invention, a mine roof prop and advancing arrangement for use with an elongated mining conveyor in longwall mining operations is provided, which comprises first and second mining prop frames each alternately energizable by pressure fluid medium from a source, independently of the other, via corresponding flow conduit means under a relatively high fluid pressure to extend such frame into supporting engagement with a mine roof thereat and under a relatively low fluid pressure to retract such frame from such engagement, energizable prop frame motive mean having first and second motive parts operatively interconnected for relative linear movement with respect to one another in said linear direction, said first motive part being connected to said first frame and said second motive part being connected to said second frame whereby when one said frame is retracted from such mine roof and the other said frame is extended into supporting engagement therewith then said motive means may be energized to effect relative linear movement between said motive parts and correspondingly relative linear movement between said frames to advance one said frame linearly in said direction with respect to the other said frame, conveyor urging piston-cylinder means including a double acting piston member and a cylinder member operatively interconnected for relative linear movement toward and away from one another and energizable by pressure fluid medium, one said member being connected to said first frame and the other said member being adapted to engage operatively such mining conveyor to urge such conveyor in a given operative linear direction in dependence upon such relative linear movement between said members, a separate flow conduit communicating respectively with the corresponding portion of said cylinder member on each side of said double acting piston member, a pressure fluid medium flow line and a return fluid medium flow line connectable to a pressure fluid medium source, and control valve means for said urging piston-cylinder means having a valve element movable automatically between an automatically controlled normally biased counter force first position and an automatically controlled fluid pressure energized second position, and movable by manual control overtake to a manual third position, said pressure flow line and said return flow line being flow connected with said separate flow conduits for said corresponding cylinder member portions through said valve means, said valve element in said second position representing a forward setting with said valve element flow communicating said flow lines with said flow conduits to move said other member away from said one member for urging disposition with respect to such conveyor in said given operative direction, said valve element in one of the remaining two of said positions representing a reverse setting with said valve element flow communicating said flow lines with said flow conduits to move said other member toward said one member for withdrawing said other member from such urging disposition with respect to such conveyor, and said valve element in the other of the remaining two of said positions representing an idle setting with said valve element flow communicating said flow conduits with each other While closing off said flow conduits from flow communication with said flow lines for placing said members in relative equalized pressure circuit idle disposition, said valve element being operatively flow connected with the corresponding flow conduit means for energizing said first prop frame to subject said valve element to the force of the prevailing fluid pressure in said first frame flow conduit means to urge said valve element to said fluid pressure energized second position, said valve means having biasing means operatively connected with said valve element to subject said valve element to a predetermined counter force to such force of the prevailing fluid pressure to urge said valve element to said normally biased counter force first position, said predetermined counter force being higher than the force of the relatively low fluid pressure in said first frame flow conduit means used for retracting such first frame from supporting engagement with the mine roof yet lower than the force of the relatively high fluid pressure in said first frame flow conduit means used for extending such first frame into such supporting engagement, and said valve means also having manual control means operatively connected with said valve element to overtake control of said valve element to move said valve element to said manual third position, whereby when said first frame is extended into roof supporting engagement the concomitant relatively high fluid pressure in said first frame flow conduit means will urge automatically said valve element to said second position representing said forward setting against the counter force of said biasing means and said other member will be moved away from said one member for attaining said urging disposition with respect to such conveyor, and when said first frame is retracted from such roof supporting engagement the concomitant relatively low fluid pressure in said first frame flow conduit means will be overcome by the counter force of said biasing means and said valve element will be urged to said first position representing one of said reverse and idle settings, the third position representing the other of said reverse and idle settings.

In accordance with one embodiment of the invention, therefore, the counter force first position corresponds with said reverse setting and said manual third position corresponds with said idle setting, while in accordance with an alternate embodiment of the invention, the counter force first position corresponds with said idle setting and said manual position corresponds with said reverse setting.

In the latter instance, in accordance with one particular feature of the invention, such arrangement also includes corresponding additional third and fourth mining prop frames each alternately energizable by additional pressure fluid medium from an additional source, independently of the other, via corresponding additional flow conduit means under a relatively high fluid pressure to extend such additional frame into supporting engagement with such mine roof and under a relatively low fluid pressure to retract such additional frame from such engagement, correspondingly additional energizable prop frame motive means for advancing in such redetermined linear direction alternately said third and fourth frames, said additional motive means having correspondingly additiona1 third and fourth motive parts operatively interconnected for relative linear movement with respect to one another in said linear direction, said third motive part being connected .to said third frame and said fourth motive part being connected to said fourth frame whereby when one said additional frame is retracted from such mine roof and the other said additional frame is extended into supporting engagement therewith then said additional motive means maybe energized to effect relative linear movement between said additional motive parts and correspondingly relative linear movement between said additional frames to advance one said additional frame linearly in said direction with respect to the other said additional frame, a linear link means interconnecting said first frame with said third frame, said one said member being connected linearly displa'ceably to said link means and correspondingly in turn thereby to said first and third frames in corresponding cooperative self-aligning resultant force linear relation, as well as a correspondingly additional said control valve means in cooperative aligned tandem flow disposition with respect to said first mentioned valve means and having a correspondingly operable additional valve element movable automatically between such first and second positions and movable by manual control overtake to such third position, whereby said pressure and return flow lines are flow connected with said separate flow conduits for said corresponding cylinder member portions through both said valve means via such corresponding valve elements, said additional valve element being operatively flow connected with the corresponding additional flow conduit means for energizing said third prop frame to subject said additional valve element to the force of the prevailing fluid pressure in said third frame flow conduit means to urge said additional valve element to such second position, said additional valve means having correspondingly [additional biasing means operatively connected with said additional valve element to subject said additional valve element to an additional redetermined counter force to such force of the prevailing fluid pressure in said third frame flow conduit means to urge said additional valve element to such normally biased counter force first position, said additional predetermined counter force vbeing higher than the force of the relatively low fluid pressure in said third frame flow conduit means used for retrac'ting such third frame, and said additional valve means also liaving additional m'anu'al control means operatively connected with said addition-a1 v-alve element to overtake control thereof to move such additional valve element to such manual third position, whereby when the corresponding force of said pressure fluid medium used for advancement of the first and second frames and the corresponding force of said additional pressure fluid medium used for advancement of said third and fourth fra'mes simultaneously exceed, respectively, the corresponding counter forces of the normal positions of both corresponding valve means said valve means will both change to the corresponding energized positions and when the corresponding counter force's of both said valve means simultaneously exceed, respectively the corresponding forces of said pressure fluid media said valve means will both change to the corresponding normal positions, and when said valve means are in correspondingly different positions said valve means will resultan'tly produce said idle disposition and be inelfective to change the existing idle flow condition of said piston-cylinder means, save for manual overtake, until both the said valve means again attain simultaneously said energized positions.

It will be appreciated that the instant specification and drawings are set forth by way [of illustration and not limitation, and that various modifications and changes may be made without departing from .the spirit and scope of the present invention which is to be limited only by the scope of the alppended claims.

What is claimed is:

1. In a mine roof prop and advancing arrangement for use with an elongated mining conveyor, including a pair of pressure fluid medium energized extensible and retractable mining prop frames, pressure fluid medium energized frame advancing motive means having a first motive part and a second motive part operatively interconnected for relative linear movement alternately toward and away from each other, one said frame being connected with one said motive part for linear movement therewith and the other said frame being connected with the other said motive part for linear movement therewith whereby to achieve alternate advancement of said frames with the respective motive part upon corresponding alternate high and low force resultant pressure fluid medium energizing of said frames and said motive means, and auxiliary pressure fluid medium energized conveyor urging piston-cylinder means including a double acting piston member and a cylinder member operatively interconnected for relative linear movement in a direction alternately toward and away from one another, one said member being connected to said one frame and the other said member being adapted to engage operatively such mining conveyor to urge such conveyor in a given operative linear direction in dependence upon such relative linear movement between said members, the improvement which comprises control valve means for controlling automatically the auxiliary pressure fluid medium for said urging piston-cylinder means and having a biasing counter force normal position and a pressure fluid medium responsive energized position, said valve means in one of said positions permitting positive flow of auxiliary pressure fluid medium to urge said urging pistoncylinder means in one of said alternate directions and said valve means in the other of said positions preventing such positive flow, said valve means being in coupled operative flow communication with the pressure fluid medium used for achieving said alternate advancement of said frames, whereby when the force of said pressure fluid medium used for advancement of said frames exceeds the counter force of the normal position of said valve means said valve means will change to said energized position and when said counter force exceeds the force of said pressure'fluid medium used for advancement of said frames said valve means will change to said normal position, to control automatically the flow of pressure fluid medium for urging said piston-cylinder means in dependence upon the difierence between said counter force and the force of said pressure fluid medium used for advancement of said frames and in turn in dependence upon the positive and non-positive flow positions of said valve means.

2. Improvement according to claim 1 wherein said valve means in said other of said positions closes off said urging piston-cylinder means from flow of auxiliary pressure fluid medium while flow communicating the pressure medium in said cylinder member on both operative sides of said double acting piston member to produce a relative equalized pressure circuit idle disposition thereof.

3. Improvement according to claim 1 wherein said valve means in said other of said positions reverses the positive flow of auxiliary pressure fluid medium to said urging piston-cylinder means to urge said urging pistoncylinder means in the other of said alternate directions.

4. Improvement according to claim 1 wherein said valve means also has a manual overtake control position, such that said valve means in one of said positions permits positive flow of auxiliary pressure fluid medium to urge said urging piston-cylinder means in one of said alternate directions, in another of said positions closes off said urging piston-cylinder means from flow of auxiliary pressure fluid medium while flow communicating the pressure medium in said cylinder member on both operative sides of said double acting piston member to produce a relative equalized pressure circuit idle disposition thereof, and in still another of said positions reverses the positive flow of auxiliary pressure fluid medium to said urging piston-cylinder means to urge said urging piston-cylinder means in the other of said alternate directions.

5. Improvement according to claim 4 wherein said counter force normal position corersponds with said still another of said positions to reverse said flow to urge said piston-cylinder means in said other of said alternate directions, said energized position corresponds with said one of said positions to urge said piston-cylinder means in said one of said alternate directions, and said manual position corresponds with said another of said positions to produce said idle disposition.

6. Improvement according to claim 4 wherein said counter force normal position corresponds with said another of said positions to produce said idle disposition, said energized position corresponds with said one of said positions to urge said piston-cylinder means in said one of said alternate directions, and said manual position corresponds with said still another of said positions to reverse said flow to urge said piston-cylinder means in said other of said alternate directions.

7. Improvement according to claim 6 wherein said arrangement also includes an additional said pair of mining prop frames and an additional said frame advancing motive means with corresponding motive parts connected respectively to said additional frames, a linear link means interconnecting said one frame of the first mentioned pair of frames with a corresponding one frame of said additional pair of frames, said one said member 'being connected to said link means and in turn thereby to said one frame of each said pairs of frames, as well as an additional said valve means in cooperative aligned tandem flow disposition with respect to said first mentioned valve means and having corresponding valve positions, said additional valve means being in coupled operative flow communication with the corresponding pressure fluid medium used for achieving alternate advancement of said additional frames, whereby when the corresponding force of said pressure fluid medium used for advancement of the first mentioned frames and the corresponding force of said pressure fluid medium used for advancement of said additional forces simultaneously exceed, respectively, the corresponding counter forces of the normal positions of both corresponding valve means said valve means will both change to the corresponding energized positions and when the corresponding counter forces of both said valve means simultaneously exceed the corresponding forces of said pressure fluid medium said valve means will both change to the corresponding normal positions, and when said valve means are in correspondingly different positions said valve means will resultantly produce said idle disposition and be ineffective to change the existing idle flow condition of said piston-cylinder means, save for manual overtake, until both said valve means again attain simultaneously said energized positions.

8. Mine roof prop and advancing arrangement for use with an'elongated mining conveyor in longwall mining operations, which comprises first and second mining prop frames each alternately energizable by pressure fluid medium from a source, independently of the other, via corresponding flow conduit means under a relatively high fluid pressure to extend such frame into supporting engagement with a mine roof thereat and under a relatively low fluid pressure to retract such frame from such engagement, energizable prop frame motive means for advancing in a predetermined linear direction alternately said first and second frames, said motive means having first and second motive parts operatively interconnected for relative linear movement with respect to one another in said linear direction, said first motive part being connected to said first frame and said second motive part being connected to said second frame whereby when one said frame is retracted from such mine roof and the other said frame is extended into supporting engagement therewith then said motive means may be energized to effect relative linear movement between said motive parts and correspondingly relative linear movement between said frames to advance one said frame linearly in said direction with respect to the other said frame, conveyor urging piston-cylinder means including a double acting piston member and a cylinder member operatively interconnected for relative linear movement toward and away from one another and energizable by pressure fluid medium, one said member being connected to said first frame and the other said member being adapted to engage operatively such mining conveyor to urge such conveyor in a given operative linear direction in dependence upon such relative linear movement between said members, a separate flow conduit communicating respectively with the corresponding portion of said cylinder member on each side of said double acting piston member, a pressure fluid medium flow line and a return fluid medium flow line connectable to a pressure fluid medium source, and control valve means for said urging piston-cylinder means having a valve element movable automatically between an automatic-ally controlled normally biased counter force first position and an automatically controlled fluid pressure energized second position, and movable by manual control overtake to a manual third position, said pressure flow line and said return flow line being flow connected with said separate flow conduits for said corresponding cylinder member portions through said valve means, said valve element in said second position representing a forward setting with said valve element flow communicating said flow lines with said flow conduits to move said other member away from said one member for urging disposition with respect to such conveyor in said given operative direction, said valve element in one of the remaining two of said positions representing a reverse setting with said valve element flow communicating said flow lines with said flow conduits to move said other member toward said one member for withdrawing said other member from such urging disposition with respect to such conveyor, and said valve element in the other of the remaining two of said positions representing an idle setting with said valve element flow communicating said flow conduits with each other while closing off said flow conduits from flow communication with said flow lines for placing said members in relative equalized pressure circuit idle disposition, said valve element being operatively flow connected with the corresponding flow conduit means for energizing said first prop frame to subject said valve element to the force of the prevailing fluid pressure in said first frame flow conduit means to urge said valve element to said fluid pressure energized second position, said valve means having biasing means operatively connected with said valve element to subject said valve element to a predetermined counter force to such force of the prevailing fluid pressure to urge said valve element to said normally biased counter force first position, said predetermined counter force being higher than the force of the relatively low fluid pressure in said first frame flow conduit means used for retracting such first frame from supporting engagement with the mine roof yet lower than the force of the relatively high fluid pressure in said first frame flow conduit means used for extending such first frame into such supporting engagement, and said valve means also having manual control means operatively connected with said valve element to overtake control of said valve element to move said valve element to said manual third position, whereby when said first frame is extended into roof supporting engagement the concomitant relatively high fluid pressure in said first frame flow conduit means will urge automatically said valve element to said second position representing said forward setting against the counter force of said biasing means and said other member will be moved away from said one member for attaining said urging disposition with respect to such conveyor, and when said first frame is retracted from such roof supporting engagement the concomitant relatively low fluid pressure in said first frame flow conduit means will be overcome by the counter force of said biasing means and said valve element will be urged to said first position representing one of said reverse and idle settings, the third position representing the other of said reverse and idle settings.

9. Arrangement according to claim 8 wherein said counter force first position corresponds with said reverse setting and said manual third position corresponds with said idle setting.

10. Arrangement according to claim 8 wherein said counter force first position corresponds with said idle setting and said manual position corresponds with said reverse setting.

11. Arrangement according to claim 10 wherein such arrangement also includes correspondingly additional third and fourth mining prop frames each alternately energizable by additional pressure fluid medium from an additional source, independently of the other, via corresponding additional flow conduit means under a relatively high fluid pressure to extend such additional frame into supporting engagement with such mine roof and under a relatively low fluid pressure to retract such additional frame from such engagement, correspondingly additional energizable prop frame motive means for advancing in such predetermined linear direction alternately said third and fourth frames, said additional motive means having correspondingly additional third and fourth motive parts operatively interconnected for relative linear movement with respect to one another in said linear direction, said third motive part being connected to said third frame and said fourth motive part being connected to said fourth frame whereby when one said additional frame is retracted from such mine roof and the other said additional frame is extended into supporting engagement therewith then said additional motive means may be energized to effect relative linear movement between said additional motive parts and correspondingly relative linear movement between said additional frames to advance one said additional frame linearly in said direction with respect to the other said additional frame, a linear link means interconnecting said first frame with said third frame, said one said member being connected linearly displaceably to said link means and correspondingly in turn thereby to said first and third frames in corresponding cooperative self-aligning resultant force linear relation, as well as a correspondingly additional said control valve means in cooperative aligned tandem flow disposition with respect to said first mentioned valve means and having a correspondingly operable additional valve element movable automatically between such first and second positions and movable by manual control overtake to such third position, whereby said pressure and return flow lines are flow connected with said separate flow conduits for said corresponding cylinder member portions through both said valve means via such corresponding valve elements, said additional valve element being operatively flow connected With the corresponding additional flow conduit means for energizing said third prop frame to subject said additional valve element to the force of the prevailing fluid pressure in said third frame flow conduit means to urge said additional valve element to such second position, said additional valve means having correspondingly additional biasing means operatively connected with said additional valve element to subject said additional valve element to an additional predetermined counter force to such force of the prevailing fluid pressure in said third frame flow conduit means to urge said additional valve element to such normally biased counter force first position, said additional predetermined counter force being higher than the force of the relatively low fluid pressure in said third frame flow conduit means used for retracting such third frame, and said additional valve means also having additional manual control means operatively connected with said additional valve element to overtake control thereof to move such additional valve element to such manual third position, whereby when the corresponding force of said pressure fluid medium used for advancement of the first and second frames and the corresponding force of said additional pressure fluid medium used for advancement of said third and fourth frames simultaneously exceed, respectively, the corresponding counter forces of the normal positions of both corresponding valve means said valve means will both change to the corresponding energized positions and when the corre sponding counter forces of both said valve means simultaneously exceed, respectively the corresponding forces of said pressure fluid media said valve means will both change to the corresponding normal positions, and when said valve means are in correspondingly dilferent posi- References Cited UNITED STATES PATENTS 2,593,039 4/1952 Livers et al 91--412 MARTIN P. SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Exan'liner. 

1. IN A MINE ROOF PROP AND ADVANCING ARRANGEMENT FOR USE WITH AN ELONGATED MINING CONVEYOR, INCLUDING A PAIR OF PRESSURE FLUID MEDIUM ENERGIZED EXTENSIBLE AND RETRACTABLE MINING PROP FRAMES, PRESSURE FLUID MEDIUM ENERGIZED FRAME ADVANCING MOTIVE MEANS HAVING A FIRST MOTIVE PART AND A SECOND MOTIVE PART OPERATIVELY INTERCONNECTED FOR RELATIVE LINEAR MOVEMENT ALTERNATELY TOWARD AND AWAY FROM EACH OTHER, ONE SAID FRAME BEING CONNECTED WITH ONE SAID MOTIVE PART FOR LINEAR MOVEMENT THEREWITH AND THE OTHER SAID FRAME BEING CONNECTED WITH THE OTHER SAID MOTIVE PART FOR LINEAR MOVEMENT THEREWITH WHEREBY TO ACHIEVE ALTERNATE ADVANCEMENT OF SAID FRAMES WITH THE RESPECTIVE MOTIVE PART UPON CORRESPONDING ALTERNATE HIGH AND LOW FORCE RESULTANT PRESSURE FLUID MEDIUM ENERGIZING OF SAID FRAMES AND SAID MOTIVE MEANS, AND AUXILIARY PRESSURE FLUID MEDIUM ENERGIZED CONVEYOR URGING PISTON-CYLINDER MEANS INCLUDING A DOUBLE ACTING PISTON MEMBER AND A CYLINDER MEMBER OPERATIVELY INTERCONNECTED FOR RELATIVE LINEAR MOVEMENT IN A DIRECTION ALTERNATELY TOWARD AND AWAY FROM ONE ANOTHER, ONE SAID MEMBER BEING CONNECTED TO SAID ONE FRAME AND THE OTHER SAID MEMBER BEING ADAPTED TO ENGAGE OPERATIVELY SUCH MINING CONVEYOR TO URGE SUCH CONVEYOR IN A GIVEN OPERATIVE LINEAR DIRECTION IN DEPENDENCE UPON SUCH RELATIVE LINEAR MOVEMENT BETWEEN SAID MEMBERS, THE IMPROVEMENT WHICH COMPRISES CONTROL VALVE MEANS FOR CONTROLLING AUTOMATICALLY THE AUXILIARY PRESSURE FLUID MEDIUM FOR SAID URGING PISTON-CYLINDER MEANS AND HAVING A BIASING COUNTER FORCE NORMAL POSITION AND A PRESSURE FLUID MEDIUM RESPONSIVE ENERGIZED POSITION, SAID VALVE MEANS IN ONE OF SAID POSITIONS PERMITTING POSITIVE FLOW OF AUXILIARY PRESSURE FLUID MEDIUM TO URGE SAID URGING PISTONCYLINDER MEANS IN ONE OF SAID ALTERNATE DIRECTIONS AND SAID VALVE MEANS IN THE OTHER OF SAID POSITIONS PREVENTING SUCH POSITIVE FLOW, SAID VALVE MEANS BEING IN COUPLED OPERATIVE FLOW COMMUNICATION WITH THE PRESSURE FLUID MEDIUM USED FOR ACHIEVING SAID ALTERNATE ADVANCEMENT OF SAID FRAMES, WHEREBY WHEN THE FORCE OF SAID PRESSURE FLUID MEDIUM USED FOR ADVANCEMENT OF SAID FRAMES EXCEEDS THE COUNTER FORCE OF THE NORMAL POSITION OF SAID VALVE MEANS SAID VALVE MEANS WILL CHANGE TO SAID ENERGIZED POSITION AND WHEN SAID COUNTER FORCE EXCEEDS THE FORCE OF SAID PRESSURE FLUID MEDIUM USED FOR ADVANCEMENT OF SAID FRAMES SAID VALVE MEANS WILL CHANGE TO SAID NORMAL POSITION, TO CONTROL AUTOMATICALLY THE FLOW OF PRESSURE FLUID MEDIUM FOR URGING SAID PISTON-CYLINDER MEANS IN DEPENDENCE UPON THE DIFFERENCE BETWEEN SAID COUNTER FORCE AND THE FORCE OF SAID PRESSURE FLUID MEDIUM USED FOR ADVANCEMENT OF SAID FRAMES AND IN TURN IN DEPENDENCE UPON THE POSITIVE AND NON-POSITIVE FLOW POSITIONS OF SAID VALVE MEANS. 